1. Field of the Invention
This invention relates to structure for selectively reducing the pressure within a pair of side-by-side chambers having a common central supply passageway, a slidable closure being movable between two operative positions determining which of the two chambers is subject to the reduced pressure at the common passageway. Each chamber is arranged with mechanism for sealing a flexible walled container therein after the contents therein have been subjected to sub-atmospheric pressure for removal of air from such contents, and structure is provided for controlling the application of the less than atmospheric pressure to the chamber being evacuated to prevent surging of a very slight pulverulent material within the flexible walled container. As another adjunct to the invention the evacuated chamber may be back flushed with an inert gas to a predetermined pressure.
2. The Prior Art
Structures for creating a condition within one of two side-by-side walled chambers are known, for example, in alternate heating and cooling of the chambers by redirecting heating gases. The following patents are illustrative of such structures:
______________________________________ Frank 134371 Murphy 1560287 Moll 1849242 ______________________________________
Patents for reducing pressure below ambient to fill a vessel are exemplified in the following:
______________________________________ Duncan RE23544 119/14.09 Hapgood 2006393 226/116 Weaver 2428598 226/116 Carter 2538411 316/31 Pechy 2760702 226/68 ______________________________________